While cruising at 9500feet with the autopilot engaged, the aircraft rolled 90 degrees, left wing down for undetermined reasons, causing the pilot to lose control of the aircraft.Findings as to Causes and Contributing Factors While cruising at 9500feet with the autopilot engaged, the aircraft rolled 90 degrees, left wing down for undetermined reasons, causing the pilot to lose control of the aircraft. The armed ELT did not activate, due to the low impact forces, and was not manually turned on, making it difficult for the rescue helicopter crew to locate the downed aircraft. The aircraft was overweight on departure from Seattle, Washington and from Kelowna, British Columbia. Therefore, for all of the previous flight and for much of the occurrence flight it was being operated outside of the envelope established by the manufacturer's flight testing.Findings as to Risk The armed ELT did not activate, due to the low impact forces, and was not manually turned on, making it difficult for the rescue helicopter crew to locate the downed aircraft. The aircraft was overweight on departure from Seattle, Washington and from Kelowna, British Columbia. Therefore, for all of the previous flight and for much of the occurrence flight it was being operated outside of the envelope established by the manufacturer's flight testing. The CAPS system was successfully deployed and likely saved the occupants from fatal injuries.Other Findings The CAPS system was successfully deployed and likely saved the occupants from fatal injuries. The aircraft's impact forces while being supported by the deployed parachute are not great enough to assure activation of the aircraft's ELT. For that reason, the Pilot's Operating Handbook and FAA Approved Airplane Flight Manual for the Cirrus Design SR20 state that after deployment of the parachute, the ELT is to be selected On. The Board is concerned that after losing control of an aircraft and deploying the parachute, the pilot may not remember to activate the ELT. Not having some form of automatic ELT activation increases the risk that the pilot will not be found in time.Safety Concern The aircraft's impact forces while being supported by the deployed parachute are not great enough to assure activation of the aircraft's ELT. For that reason, the Pilot's Operating Handbook and FAA Approved Airplane Flight Manual for the Cirrus Design SR20 state that after deployment of the parachute, the ELT is to be selected On. The Board is concerned that after losing control of an aircraft and deploying the parachute, the pilot may not remember to activate the ELT. Not having some form of automatic ELT activation increases the risk that the pilot will not be found in time.